Dental caries is a major dental disease that affects the majority of the population. In the early part of the 20th century, investigators discovered that fluoride was effective in reducing the incidence of caries. Since that time, fluoride research has developed, and it is now well accepted that fluoride treatments benefit dental health.
Most dentifrice compositions contain fluoride ions in the range of 1,000 to 1,500 ppm. However, for some segments of the population, higher amounts of fluoride may be even more beneficial. Some patients often suffer from either aggressive caries, or are otherwise at a higher risk of dental decay than the general population. Other patients suffer from xerostomia, or tooth sensitivity. These patients may benefit from special dentifrices that incorporate high levels of fluoride ions. For example, some such dentifrices incorporate sodium fluoride as a fluoride ion source, in amounts of over 1,500 ppm, such as around 2,000 ppm or around 5,000 ppm.
However, it may be difficult to maintain the effective properties of high levels of fluoride in oral care compositions. Fluoride ion sources may have low solubility, fluoride ions may precipitate out of a dentifrice composition and fluoride ions may react with other ingredients in a dentifrice composition. On the other hand, if more solvent is added to the composition to increase fluoride ion availability, the composition changes and tends to lose the desirable physical characteristics associated with an acceptable dentifrice, e.g., the viscosity of the compositions may be too thin and runny.
The use of mucoadhesive polymers in combination with fluoride is known in the art. However, ionic salts, including fluoride ions known to interact and become entrapped in multiple polymers, causes a reduction of available fluoride ions. Additionally, typical toothpaste compositions containing mucoadhesive polymers may experience undesirable “stickiness” or “tackiness” in the mouth following use.
Thus, there is a need in the art for a high-fluoride content oral care compositions, e.g., for patients who need high levels of fluoride, e.g., those suffering from xerostomia and/or tooth sensitivity. It is further desirable to develop such a composition in which the anticaries activity of the fluoride ion is maintained successfully over time. It is also desirable to develop compositions which do not result in a sticky or tacky sensation following use, and provides a smooth feel during and after brushing.